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The differential rotation of anti-solar type detected by observations for several stars may result from a fast meridional flow. The sufficiently intensive meridional circulation may be caused by large-scale thermal inhomogeneities or,…

Astrophysics · Physics 2009-11-10 L. L. Kitchatinov , G. Ruediger

We investigate the surface spot activity of the rapidly rotating, lithium-rich active single K-giant DI Psc to measure the surface differential rotation and understand the mechanisms behind the Li-enrichment. Doppler imaging was applied to…

Solar and Stellar Astrophysics · Physics 2015-06-22 L. Kriskovics , Zs. Kővári , K. Vida , T. Granzer , K. Oláh

Oscillations of coronal loops in the Sun have been reported in both imaging and spectral observations at the onset of flares. Images reveal transverse oscillations, whereas spectra detect line-of-sight velocity or Doppler-shift…

Solar and Stellar Astrophysics · Physics 2015-05-27 Danica Tothova , Davina Innes , Guillermo Stenborg

The sunspot drawings of Johann Staudacher of 1749--1799 were used to determine the solar differential rotation in that period. These drawings of the full disk lack any indication of their orientation. We used a Bayesian estimator to obtain…

Solar and Stellar Astrophysics · Physics 2015-06-05 R. Arlt , H. -E. Froehlich

(abridged) Context: Solar-like differential rotation is characterized by a rapidly rotating equator and slower poles. However, theoretical models and numerical simulations can result in a slower equator and faster poles when the rotation is…

Solar and Stellar Astrophysics · Physics 2014-10-17 P. J. Käpylä , M. J. Käpylä , A. Brandenburg

We present the results of a Doppler tomographic reconstruction of the UV spectra of the double-lined, O binary HD 100213 based on observations made with the International Ultraviolet Explorer (IUE). We used cross-correlation methods to…

Solar and Stellar Astrophysics · Physics 2010-11-11 Laura R. Penny , Cynthia Ouzts , Douglas R. Gies

Simulations of magnetohydrodynamics convection in slowly rotating stars predict anti-solar differential rotation (DR) in which the equator rotates slower than poles. This anti-solar DR in the usual $\alpha \Omega$ dynamo model does not…

Solar and Stellar Astrophysics · Physics 2020-01-01 Bidya Binay Karak , Aparna Tomar , Vindya Vashishth

Differential rotation is one of the basic characteristics of the Sun, and it plays an important role in generating the magnetic fields and its activities. We investigated rotation rate using chromospheric features such as plages, enhanced…

Solar and Stellar Astrophysics · Physics 2024-05-14 Hema Kharayat , Jagdev Singh , Muthu Priyal , B. Ravindra

We present time-series Doppler images of the rapidly-rotating active binary star EI Eri from spectroscopic observations collected during the MUSICOS multi-site campaign in 1998, since the critical rotation period of 1.947 days makes it…

Astrophysics · Physics 2015-05-13 Zs. Kővári , A. Washuettl , B. H. Foing , K. Vida , J. Bartus , K. Oláh , the MUSICOS 98 team

We present ~2000 polarimetric and ~3000 photometric observations of 15 gamma-ray bright blazars over a period of 936 days (11/10/2008 - 26/10/2012) using data from the Tuorla blazar monitoring program (KVA DIPOL) and Liverpool Telescope…

High Energy Astrophysical Phenomena · Physics 2016-09-15 H. Jermak , I. A. Steele , E. Lindfors , T. Hovatta , K. Nilsson , G. P. Lamb , C. Mundell , U. Barres de Almeida , A. Berdyugin , V. Kadenius , R. Reinthal , L. Takalo

The global rotational profile of the solar atmosphere and its variation at different layers, although crucial for a comprehensive understanding of the dynamics of the solar magnetic field, has been a subject to contradictory results…

Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of…

Solar and Stellar Astrophysics · Physics 2017-05-12 Chang Liu , Yan Xu , Wenda Cao , Na Deng , Jeongwoo Lee , Hugh S. Hudson , Dale E. Gary , Jiasheng Wang , Ju Jing , Haimin Wang

The solar photosphere, chromosphere and corona are known to rotate differentially as a function of latitude. To date, it is unclear if the solar transition region also rotates differentially. In this paper, we investigate differential…

Solar and Stellar Astrophysics · Physics 2021-07-21 Jaidev Sharma , Brajesh Kumar , Anil K Malik , Hari Om Vats

Brightness variations due to dark spots on the stellar surface encode information about stellar surface rotation and magnetic activity. In this work, we analyze the Kepler long-cadence data of 26,521 main-sequence stars of spectral types M…

Solar and Stellar Astrophysics · Physics 2019-09-30 A. R. G. Santos , R. A. García , S. Mathur , L. Bugnet , J. L. van Saders , T. S. Metcalfe , G. V. A. Simonian , M. H. Pinsonneault

To explore the physics of large-scale flows in solar-like stars, we perform 3D anelastic simulations of rotating convection for global models with stratification resembling the solar interior. The numerical method is based on an implicit…

Solar and Stellar Astrophysics · Physics 2013-12-10 G. Guerrero , P. K. Smolarkiewicz , A. G. Kosovichev , N. N. Mansour

Anti-solar differential rotation profiles have been found for decades in numerical simulations of convective envelopes of solar-type stars. These profiles are characterized by a slow equator and fast poles (i.e., reversed with respect to…

We present the first measurements of surface differential rotation on a pre-main sequence binary system. Using intensity (Stokes I) and circularly polarised (Stokes V) timeseries spectra, taken over eleven nights at the Anglo-Australian…

Kepler ultra-high precision photometry of long and continuous observations provides a unique dataset in which surface rotation and variability can be studied for thousands of stars. Because many of these old field stars also have…

We compute the differential rotation of main sequence stars of the spectral types F, G, K, and M by solving the equation of motion and the equation of convective heat transport in a mean-field formulation. For each spectral type the…

Astrophysics · Physics 2009-11-11 M. Kueker , G. Ruediger

The main aim of this work is to determine the solar differential rotation by tracing sunspot groups during the period 1964-2016, using the Kanzelh\"ohe Observatory for Solar and Environmental Research (KSO) sunspot drawings and white light…